Question

Ohm's law in point form in field theory can be expressed as
1. \(V = IR\)
2. \(J = \frac{\sigma }{E}\)
3. \(J = \sigma E\)
4. None of the above

Answer 1

Correct Answer - Option 3 : \(J = \sigma E\)

CONCEPT:

• Ohm's law: At constant temperature, the potential difference across a current-carrying wire is directly proportional to the current flowing through it.

⇒ V = IR

 Where V is the potential difference, R is resistance and I is current

• The conductors generally obey the ohm's law​
• Ohm's law in point form or vector form: The vector form of Ohm’s law is used in electromagnetics and material science.
• The vector form is also known as the point form of Ohm's law.

⇒​ J = σE 

Where J is the current density, E is the electric field and σ is conductivity.

• Conductivity is the reciprocal of resistivity. 

EXPLAINATION:

• From the above discussion, it is clear that the ohms law in point or vector for is given by

⇒​ J = σE 

• Hence, the correct option is (3).